Note: although we provide a MonadBaseControl instance, lifted-base's
fork function is incompatible with the underlying ResourceT system.
Instead, if you must fork a separate thread, you should use
resourceForkIO.

Using fork usually leads to an exception that says
"Control.Monad.Trans.Resource.register': The mutable state is being accessed
after cleanup. Please contact the maintainers."

An extension of the basic WAI Application datatype to provide extra
features needed by Yesod. Users should never need to use this directly, as
the HandlerT monad and template haskell code should hide it away.